Polythioether impression material

ABSTRACT

A colorable, pleasant smelling, quick setting, putty-like polythioether polymer material formed by reacting a mercaptan and a diacrylate with the aid of a peroxide catalyst.

United States Patent Weaver 1 1 Oct. 14, 1975 54] POLYTHIOETHERIMPRESSION 3,751,399 /1973 bee etal 32/15 MATERIAL OTHER PUBLICATIONS Inventor: Benjamin Weaver, Detroit, Mich.

Sybron Corporation, Rochester, N .Y.

Filed: Jan. 28, 1974 Appl. No.: 437,234

Assignee:

References Cited UNITED STATES PATENTS 6/1951 Knock et a1. 32/107 10/1967 Sheard 260/791 5/ 1973 Berenbaum et a1 260/79.1

Anderson Applied Dental Matls., (3rd ed.), (Blackwell Sci. Pub.), (Oxford, 0 England), (1967), pp. 217-219.

Combe Notes on Dental Matls., (Churchill Livingstone), (London), (1972), pp. 141-442.

Primary Examiner-M. J. Welsh Assistant Examiner-H. H. Fletcher Attorney, Agent, or Firm--'Iheodore B. Roessel; Papan Devnani ABSTRACT A colorable, pleasant smelling, quick setting, puttylike polythioether polymer material formed by reacting a mercaptan and a diacr'ylate with the aid of a peroxide catalyst.

5 Claims, No Drawings POLYTIIIOETHER IMPRESSION MATERIAL BACKGROUND OF THE INVENTION The present invention relates to a dental impression material and more particularly to a polythioether impression material. In current practice a two paste system containing polymeric mercaptan, plasticizers, sulfur, lead peroxide and a filler is used by dentists to take impressions of patients teeth. Such impressions are used by the dentist to make crowns, dentures, or the like. When mixed, usually with a spatula on a paper pad a polymerizable material is formed which the dentist applies to the teeth to produce a custom dental tray. When set, the polymerized material is removed and this custom dental tray used as a mold in making the crown or denture.

The two paste system of the prior art, however, has a relatively long setting time and the fact that the material contains lead may make it somewhat objectionable to the dentist. Furthermore the prior art mixture is an unsightly brown color and has an offensive odor due to the presence of low molecular weight sulfur compounds. For these reasons, putting such a material into the patients mouth and the taking of a dental impression, often proved to be an unpleasant and traumatic experience. During the time the impression is being taken the patient must keep his mouth steady and immobile and since the curing time of the prior art material is six minutes it is difficult for the patient to do this.

The drawbacks of the prior art are overcome in the present invention by providing an impression material which is lead-free, pleasant smelling, quick setting, and colorable.

SUMMARY OF THE INVENTION OBJECTS OF THE INVENTION One object of the invention is to provide a polymeric impression material which can be admixed and is aesthetically pleasing.

Another object of the invention is toprovide a ploythioether dental impression material.

A further object of the present invention is to provide a dimensionally stable dental impression material which has a pleasant odor and which can be given any color.

Yet another object is to provide a dental impression material capable of hardening in approximately [2 minutes.

DETAILED DESCRIPTION OF THE INVENTION The polythioether polymer material of this invention is used for making impression and imprints and serves as a mold from which a similar article could be reproduced. In the uncured stage the polymer has a puttylike consistency. An impression of a shape or a contour is made upon it. Upon curing the polymer hardens and retains the impression. The polymeric material has non-adhering properties and releases itself easily from the object whose impression is made.

The polythioether impression material of the invention is a polymeric system based on the use of: (l) a mercaptan terminated polymer, more specifically a mercaptan terminated bis(oxyethylene)methane containing disulfide linkage with a small amount of thio groups in the chain, having a molecular weight of 4,000; (2) a di, tri or tetra-acrylate monomer such as hexane diol diacrylate or polyethyleneglycol diacrylate or trimethylolpropane triacrylate; and (3) a peroxide preferably calcium peroxide.

The mercaptan terminated polymer suitable for use in the present invention will in general have a functionality of two or greater and will be of a high molecular weight but still liquid and fluid. It may also contain various amounts of mercapto groups in the chain for crosslinking purposes. The polymers should have molecular weights ranging from l0004000 and may contain various percentages of mercapto groups on the molecular chain. The mercapto groups are available for crosslinking the acrylic monomers. Many polymers meeting this description are commercially available. We have found products manufactured by Thiokol Chemical Co. under the trade name LP-Z, LP-33, etc. to be particularly useful.

Some examples of di, tri and tetra acrylated monomers and polymers are propylene glycol diacrylate, butylene glycol diacrylate, hexane diol diacrylate, tri methylol propane triacrylate, pentaerythritol tetraacrylate, and polyethylene glycol diacrylate. Properties of the polymerizable system will depend upon the acrylate chosen and the amount used. Functionality of acrylates is chosen to get optimum physical properties in the finished custom dental tray which is used as the mold. With the increase in functionality physical properties such as hardness, and rigidity increases. The excessive amounts lead to shorter pot life, brittleness and higher shrinkage. The molecular weight of acrylate can affect rigidity, elasticity, as well as working time. High molecular weight acrylates such as polyethylene diacrylate produce soft elastic, non-rigid polymers. Hexane diol diacrylate produces polymers having increased hardness and rigidity. Tri acrylates would produce corresponding results depending upon molecular weight. For our purposes we have found that an excess of stoichiometric equivalents is desirable, although less amounts can be used if modifications are desirable in the work ing characteristics.

Along with the mercaptan terminated polymer and acrylic monomers the use of appropriate fillers is quite necessary to reinforce the set material. Many fillers known in the elastomeric field could be used, such as: calcium carbonate, calcium oxide, magnesium oxide, magnesium sulfate, strontium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfate, zinc sulfide, zinc chloride, aluminum oxide, silica, antimony oxides, tin oxides, and others. As in most elastomeric applications particle size and surface behavior are important considerations in filler selection.

The plasticizers are used to control the consistency of the hand moldable putty. A number of plasticizers are available for use, depending upon particular properties desired. We have found a low molecular weight liquid styrene polymer to be quite useful as a plasticizer. Suitable plasticizers are those having the viscosity in the range 2000-50000 cps at ambient tempera- Color, Gardner v 2.5 Viscosity at 77F.. poise 120-200 Volatility 2 hrs. at 311F.- .557: Volatility 4 hrs. at 31 1F. 1.29%

Flash point F. open cup Fire point F. open cup 300 maximum 350 maximum Pour point F 50 Refractive lndex 1.58 Sp. G. at 77F. 1.03

Metal peroxides are utilized as reactive components. These include zinc peroxide, tin peroxide, antimony peroxide, lead peroxide, manganese peroxide, barium peroxide, strontium peroxide, calcium peroxide, magnesium peroxide, and others. We have also found that hydroperoxides such as cumene hydroperoxide can be useful. For our purposes we have found calcium peroxide to be most desirable because of its good reactivity, good handling, acceptable color and low potential toxicity. Water and amines such as triethylolamine can be further used to accelerate the reaction and improve the physical properties. 1

These components are formed into two pastes, one containing primarily the base and the other the catalyst. The catalyst component in addition includes the metal peroxide.

A typical base component formed according to the present invention would include:

Mercaptan Polymer (LP-2) 100.00 parts by wt. Hexane Diol Diacrylate 6.00 parts by wt. Filler (silica) 200.00 parts by wt. Mineral Oil 10.00 parts by wt. Perfume trace parts by wt. Pigment trace parts by wt. Water 2.00 parts by wt.

The catalyst component typically would include:

Plasticizer TP-680 70.00 parts by wt. Triethylolamine 5.00 parts by wt. CaO 100.00 parts by wt. Filler (Silica) 190.00 pans by wt. Mineral Oil 15.00 parts by wt.

In order to form a dental impression material according to the present invention, two parts of the base is admixed with one part of the catalyst.

The base and catalyst can be mixed together in the hands and when molded and set, produce a rigid high durometer material having a hardness of 75-80 on a Shore A durometer. The material sets in l minutes and because of absence of low molecular weight sulfur compounds it is void of offensive odor. The ratio of base to catalyst could be varied to control the setting time between [-5 minutes. An increase in the catalyst amount shortens the time. Another successful formula for these components would include:

Polymercaptzm 100.00 parts by weight ZnS 23.00 parts by weight 5 Trimethylol 2.00 parts by weight propane triacrylate parts by weight Hexane diol diacrylate r 2.00 parts by weight Water 1.50 parts by weight Catalyst v i Calcium peroxide 100.00 parts by weight Magnesium oxide 10.00 parts by weight Zinc oxide 100.00 parts by weight Plasticizer (TP-680) 175.00 parts by weight Mineral oil 5.00 parts by weight Silicone Oil 1000 parts by weight Thus, it should be appreciated that the present invention accomplishes its intended objectives in providing a dental impression material which smells good, is aesthetically pleasant, colorable, easy to handle, and sets in 1 /2 minutes instead of 6 minutes thereby saving a dentists time. In addition it is so easy to form a custom tray it saves an additional visit by the patient to the dentist.

Ideally, the polymeric material is most suited as a dental impression material. It could also be used in making reproductions of carvings and sculptures. The impression material is applied on the surface of the sculpture and removed upon hardening. This matrix could then be used to make more copies of the sculpture.

Having described the invention in detail, what is 30 claimed as new is:

1. An impression material formed by polymerization by mixing together two paste like components:

a. component one comprising;

i. an acrylate monomer selected from a group consisting of hexanediol diacrylate, polyethylene glycol diacrylate and trimethylolpropane triacrylate,

ii. a mercaptan terminated polymer of molecular weight 1000-4000, having mercaptan groups available for crosslinking with said monomer, and

iii. said acrylate monomer making up about 6 parts by weight and said polymer making up about 100 parts by weight of component one;

b. component two comprising;

i. alpha methyl styrene oligomer as plasticizer,

ii. a peroxide catalyst for initiating a reaction between said polymer and monomer of component one;

iii. triethylolamine as accelerator for reaction;

iv. said plasticizer making up 70 parts by weight,

peroxide catalyst 100 parts by weight and triethylolamine 5 parts by weight of component two;

and a I c. components one and two each further comprising 190-200 parts by weight a filler and 10-15 parts by weight mineral oil.

2. Material of claim 1 wherein the filler is silica.

3. Material of claim 1 wherein thecatalyst is calcium peroxide.

4. Material of claim 1 wherein saidmaterial contains a perfume.

5. Material of claim 1 wherein said material contains a pigment.

speeding the UNITED STATES PATENT QFFICE CERTIFICATE OF CORRECTION Patent No. 3,912,758 Dated October 14, 1975 Ben 'amin Weaver Inventor-(s) 3 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column line 57, change "1/2" to 1 1/2 Column 2; line 15, after "two" insert (2) I line 27, change "'aci'ylated" to acrylate M1 Column 3, line 55, the entire equation should be deleted 0 I Bigncd and Scaled this twentieth D y f January 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Office Commissioner of Patents and Trademarks 

1. AN IMPRESSION MATERIAL FORMED BY POLYMERIZATION BY MIXING TOGETHER TWO PASTE LIKE COMPONENTS: A. COMPONENT ONE COMPRISING, I. AN ACRYLATE MONOMER SELECTED FROM A GROUP CONSISTING OF HEXANEDIOL DIACRYLATE, POLYETHYLENE GLYCOL DIACRYLATE AND TRIMETHYLOLPROPANE TRIACRYLATE, II. A MERCAPTAN TERMINATED POLYMER OF MOLECULAR WEIGHT 1000-4000, HAVING MERCAPTAN GROUPS AVAILABLE FOR CROSSLINKED WITH SAID MONOMER, AND III. SAID ACRYLATE MONOMER MAKING UP ABOUT 6 PARTS BY WEIGHT AND SAID POLYMER MAKING UP ABOUT 100 PARTS BY WEIGHT OF COMPONENT ONE, B. COMPONENT TWO COMPRISING, I. ALPHA METHYL STYRENE OLIGOMER AS PLASTICIZER, II. A PERIOXIDE CATALYST FOR INITIATING A REACTION BETWEEN SAID POLYMER AND MONOMER OF COMPONENT ONE, III. TRIETHYLOLAMINE AS ACCELERATOR FOR SPEEDING THE REACTION, 1V. SAID PLASTICIZER MAKING UP 70 PARTS BY WEIGHT, PERIOXIDE CATALYST 100 PARTS BY WEIGHT AND TRIETHYLOLAMINE 5 PARTS BY WEIGHT OF COMPONENT TWO, AND C. COMPONENTS ONE AND TWO EACH FURTHER COMPRISING 190-200 PARTS BY WEIGHT A FILLER AND 10-15 PARTS BY WEIGHT MINERAL OIL.
 2. Material of claim 1 wherein the filler is silica.
 3. Material of claim 1 wherein the catalyst is calcium peroxide.
 4. Material of claim 1 wherein said material contains a perfume.
 5. Material of claim 1 wherein said material contains a pigment. 